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Evaporative-pattern casting is a type of casting process that uses a pattern made from a material that will evaporate when the molten metal is poured into the molding cavity. The most common evaporative-pattern material used is polystyrene foam. [1] The two major evaporative-pattern casting processes are: [1] Lost-foam casting; Full-mold casting
Direct injection expanded foam molding (also known as injection molded foam) is a manufacturing process that creates soft foam products direct from a compound into a final product. [1] This process eliminates the steps normally required for die-cutting and compression molding , because it manufactures the foam and the product, simultaneously.
Polyethylene bead foams (including) EPE can be used to replace both polystyrene foam, and both rigid and flexible polyurethane. Uses include cushioning applications, and impact absorption applications including packaging. [4] Consumption of polyethylene for PE foam was estimated at 114x10 6 kg in 2001. The majority was used for non-crosslinked ...
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The direct molding method is to make the wax material into the same wax mold as the casting by hand or other tools; the indirect molding method is to make the wax mold through the mold. The direct molding method requires craftsmen to have a high technical level; otherwise, the quality of castings cannot be guaranteed.
As compared to investment casting, it is cheaper because it is a simpler process and the foam is cheaper than the wax. Risers are not usually required due to the nature of the process; because the molten metal vaporizes the foam the first metal into the mold cools more quickly than the rest, which results in natural directional solidification ...
The bubble/foam-making process is irreversible and endothermic, i.e. it needs heat (e.g. from a melt process or the chemical exotherm due to cross-linking), to volatilize a liquid blowing agent. However, on cooling process, the blowing agent will condense, which is a reversible process. [2] [3]
Depending on the gas, the foam's density can be between 5% and 99% of the pre-processed plastic. [2] Design parameters, focused on the foam's final form and the molding process afterward, include the type of die or mold to be used, as well as the dimensions of the bubbles, or cells, that classify the material as a foam. [1]